GETTYSBURG, Pa. -- We are met on a great battlefield of the Civil War.

It was here 150 years ago that the war turned, that its conclusion, while not visible, was at least imaginable. And it was here, four months later, that a 270-word speech transformed the war from a struggle to save the Union to one to save the soul of the country.

Many acts of heroism occurred here, most of them lost to history.

Many acts of folly and futility occurred here, one of them (Pickett's Charge) preserved in a thousand histories and in a nation's collective memory.

Ten remarkable sentences of enduring wisdom were uttered here, memorized by generations of Americans who share the liberty that Abraham Lincoln assured was won here.

Pressed into the soil here were the footfalls of Robert E. Lee, George G. Meade and George Pickett; of 50,000 men who would be counted as casualties; of many multiples more who would survive; and, in November 1863, of Lincoln himself, making Gettysburg perhaps the only American town of 2,400 people ever to bear witness to the toil of so many figures of such grandeur.

Gettysburg is more than three times bigger than it was a century and a half ago, but it remains one of the few towns of its size that does not require a state to identify its location.

Gettysburg is not so much a Pennsylvania town as an American icon. Like Valley Forge, it belongs to our common history more than to the commonwealth of Pennsylvania. Both are obscure corners of the country sanctified by sacrifice -- consecrated, you might say, far above our poor power to add or detract.

But here, even more than at Valley Forge, we feel the terrible toll of the terrible swift sword, the great losses suffered by warriors from both sides when men abandoned the altars of the evening dews and damps and slipped quietly into battle, some of them moving silently to their violent deaths.

• • •

My feelings at this time can be readily described, as but one thought was paramount, a hope that the troops in front would be able to thrash the confederates (sic) without our aid, for with rest comes a dislike for bloody encounters.

-- Francis Adams Donaldson, company commander in the 118th Pennsylvania Infantry and veteran of Shepherdstown, Fredericksburg and Chancellorsville

The beginning of July 1863 was a peculiar American moment -- a time when the destiny of a continent began to be clarified -- but it was not an inevitable moment. In March 1865, in his Second Inaugural Address, Lincoln would note that soldiers and sympathizers of both sides "read the same Bible and pray to the same God, and each invokes His aid against the other." Union forces may have come to believe that they moved with God's gusts at their back, but before Gettysburg the resolution of the war was anything but certain.

Antietam lit the way, and with a Union victory at a creek there the previous September, Lincoln felt sufficient confidence to contemplate his Emancipation Proclamation. But Gettysburg may be the better dividing line, and 1863, like 1963 a century later, might be the better benchmark to see a world transformed.

The year 1863 marked the passing of some of the symbolic figures of the old era. Besides Stonewall Jackson, who had died at Chancellorsville two months before the fighting at Gettysburg, these giants of a world that itself was perishing left this Earth: Sam Houston, Eugene Delacroix, William Makepeace Thackeray.

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There was no shade, & the heat of the sun was almost insupportable. A heavy cannonading was kept up -- a great many shells passing over us -- and some from our own batteries exploded over our line & killed men.

-- from the diary of Samuel Pickens, member of the 5th Alabama Infantry

By the dim and flaring lamps of 150 years of perspective we now see that Gettysburg split the Civil War into two halves, before and after, much like the war split the country in two, setting state against state and sometimes brother against brother. It was here at Gettysburg that, as Allen C. Guelzo writes in his portrait of the battle published earlier this month, "two great armies, bound for the greatest and most violent collision the North American continent had ever seen," moved toward their fateful intersection.

The year 1863 also stands as a dividing line between two eras, both in the New World and in the Old, which watched nervously as the United States fell apart, destabilizing the global economy, especially the textile markets ruled by the vicissitudes of the cotton trade.

It was the year when ground was broken on the transcontinental railroad and when Jules Verne published "Five Weeks in a Balloon," both pointing to a future when engineering and scientific exploration would shape the world.

In that year, six men who would play major roles in the decades to come were born: Franz Ferdinand and David Lloyd George, one whose assassination at Sarajevo would start World War I, the other whose work at Versailles would end World War I; William Randolph Hearst, who would boast of starting a war and who would personify the growth of big media; Henry Ford, who would make the world mobile with his Model T but render workers immobile with his assembly line; Edvard Munch, whose scream against modernity would resonate even in our own time; and Black Elk, the Lakota Sioux holy man and visionary who would change our view of the conquest of the continent his people once dominated.

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When our great victory was just over, the exultation of victory was so great that one didn't think of our fearful losses, but now I cant [sic] help feeling a great weight at my heart.

-- Henry Livermore Abbott, commander of a company in the 20th Massachusetts Infantry

The importance of the Union victory at Gettysburg was evident instantly. George Templeton Strong, the lawyer whose diary gives us an intimate, contemporaneous view of the Civil War era, recognized immediately that the battle removed Philadelphia, Washington and Baltimore from the danger of raids, perhaps even occupation, by Confederate forces and ended the cult of invincibility that Union soldiers had built up around their rival, Robert E. Lee.

Several times Strong was stopped in the street and told, "This ends the Rebellion." It would not end, of course, for another 21 months, and the road from Gettysburg to Appomattox Court House, where Lee surrendered to Ulysses S. Grant, would be strewn with death and destruction.

Grant and his Army of the Tennessee would prevail at Vicksburg after a siege of nearly seven weeks, the Confederate surrender coming a day after the end of the conflict at Gettysburg. Together, Gettysburg and Vicksburg provided unmistakable evidence of the superiority of the Union effort; the Confederacy was sliced into two parts and its hold on the Mississippi was broken, prompting Lincoln to write his Springfield, Ill., friend James C. Conkling, "The Father of Waters again goes unvexed to the sea."

But no mention of Vicksburg appears in the Strong diaries -- an omission that historians Allan Nevins and Milton Halsey Thomas, editors of the diary that was discovered in the 1930s, attribute to "how completely the eastern battle held possession of the minds of New Yorkers."

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There are no words in the English language to express the sufferings I have witnessed today. The men lie on the ground; their clothes have been cut off them to dress their wounds; they are half naked, have nothing but hard-tack to eat.

-- Cornelia Hancock, the first nurse to reach one of the Union divisions after the battle

Gettysburg and Vicksburg alone would make this a tumultuous time, as this story's quotes from the Library of America's volume on the third year of the Civil War demonstrate. But before the fortnight was out -- when the exchanges of rifle and cannon fire were stilled -- New York would bear witness to draft riots underlining tensions in the North that would endure beyond the war.

These riots were fomented by resentments not only over the ability of wealthy Americans to buy their way out of conscription, but also by worries that the addition of newly freed blacks to the workforce would reduce the wages of recent white immigrants.

The America that would emerge out of the Civil War would be riven by such resentments, and by the tensions produced by an industrializing nation struggling to reach its economic potential, redeem its political promises, rebuild its ravaged countryside and heal its deep emotional wounds, all at the same time.

That struggle has not been completed even now, a century and a half later, a reminder that, as Osmar White wrote of those who survived World War II, "The living have the cause of the dead in trust."

It was during the Civil War that the Dostoyevsky brothers published Alexander Ostrovsky's play "Sin and Sorrow Are Common to All," which premiered on stage in 1863. It provided the leitmotif for the year, a year in which the soldiers of Gettysburg died to make men free and in which a country lawyer, while dedicating and consecrating the cemetery at Gettysburg, gave his country a new birth of freedom.